Is a person afflicted with a cold or influenza sinful if they attend gatherings and transmit the illness to others, despite knowing of their infection?

A sick person is only prevented from mixing with healthy people if their illness is harmful to others and poses an obvious risk and contagion, such as leprosy, where the ruler must prevent those afflicted from mixing with healthy people and house them in a separate place. As for the common cold and flu, the affected person is not prevented from mixing with people, as these are common illnesses with limited contagion that is neither rapid nor dangerous. Indeed, people sneezed multiple times in the presence of the Prophet, peace and blessings be upon him, and he did not prevent them from sitting with him. However, there are dangerous types of influenza about which doctors warn of their severity and caution against mixing with those afflicted. It is recommended that the sick person place a tissue over their nose and mouth when coughing and sneezing. It is not permissible for them to attend congregational prayers (Jama'ah) or Friday prayers (Jumu'ah) if the cold is severe and harms others.